Other head and neck

Question 1

Oral tumour with islands / cords set within fibrous stroma with hyperchromatic peripherally palisaded cells (with reverse polarity and subnuclear vacuoles) and central regions resembling stellate reticulum.

Answer 1

Ameloblastoma

Plan:
Correlate with clinical history and radiology (?mandible lesion)
Examine further blocks (e.g. for total size, relation to margins, areas of differing morphology)
IPX to support Dx: CK5, CK19, BRAF V600E
Next steps: Synoptic report, discuss at MDT

Question 2

Nasal polyp with fibrous stroma rich in bland spindle cells and vascular spaces of various sizes

Answer 2

Juvenile nasopharyngeal angiofibroma

Differential diagnosis:
Haemangioma
Normal nasal turbinate

Plan:
Correlate with clinical history and radiology (?pre-operative angiography)
IPX to support Dx: AR, beta catenin (positive in stromal cells, nuclear beta catenin)
No specific further action required for this benign diagnosis

Question 3

Head/neck tumour with poorly differentiated malignant epithelial cells with syncytial growth, admixed with a prominent lymphocytic infiltrate. Cells have vesicular nuclei with macronucleoli.

Answer 3

Naropharyngeal carcinoma

Differential diagnosis:
DLBCL
Non-keratinsing SCC
Melanoma
Rhabdomyosarcoma
Other poorly differentiated carcinomas (sinonasal undifferentiated carcinoma, NUT carcinoma, SWI/SNF deficient carcinoma)

Plan:
Correlate with clinical history (?patient from endemic area)
Examine further blocks
IPX to support Dx: AE1/AE3, p40, EBER ISH (expect positive)
IPX to discount DDx: CD45 and CD20, p16, S100 and SOX10 and Melan A, desmin and myogenin, NUT, SMARC proteins
Molecular: NGS for IDH mutation if suspect SNUC after IPX
Next steps: Synoptic report, discuss at MDT

Question 4

Oral cyst with fibrous cyst wall with flat non-keratinising squamous epithelium 2 - 4 layers thick

Answer 4

Dentigerous cyst

DDx
Periapical cyst (if inflamed)

Plan:
Correlate with clinical history and radiology (?assiociated with crown of unerupted tooth)
IPX: Not required for diagnosis
No specific further action required for this benign diagnosis

Question 5

Oral cyst with fibrous cyst wall with stratified squamous lining with flat palisaded basal layer (lacking rete ridges) and surface with corrugated parakeratosis

Answer 5

Odontogenic keratocyst

Plan:
Correlate with clinical history and radiology
No specific IPX or molecular available
Advice to clinician: Locally aggressive, may recur if incompletely excised

Question 6

Small blue round cell tumor of head/neck with lobulated growth pattern and abundant neuropil. Homer Wright pseudorosettes and Flexner-Wintersteiner (true) rosettes may be seen

Answer 6

Olfactory neuroblastoma

DDx
Sarcomas: Ewing’s, Rhabdomyosarcoma
Lymphoma
Melanoma
Poorly differentiated carcinoma: Small cell neuroendocrine, sinonasal undifferentiated carcinoma, NUT carcinoma, SWI/SNF deficient carcinoma

Plan:
Correlate with clinical history and radiology (?cribriform plate tumour)
Examine further blocks
IPX to support Dx: Synaptophysin, chromogranin, neurofilament (expect positive) IPX to discount DDx: CD99 and FLI1, desmin and myogenin, CD45, SOX10 and Melan A, AE1/AE3 and CAM5.2
Next steps: Hyams grade, Kadish stage, synoptic report, discuss at MDT

Question 7

Oral cavity tumour made of large cells with abundant fibrillar eosinophilic cytoplasm with cross striations, without nuclear atypia

Answer 7

Adult type rhabdomyoma

Differential diagnosis:
Granular cell tumour
Oncocytoma

Plan:
Correlate with clinical history and radiology
Examine further blocks (e.g. for size, relation to margins, areas of differing morphology)
IPX to support Dx: Myogenin, MyoD1
IPX to discount DDx: CD68, S100, AE1/AE3
No specific action required for this benign diagnosis